1. Field of the Invention
The present invention generally relates to a recording head for use in an electrically excited transfer recording device, and more particularly, to the structure of a recording head for use in a transfer recording device of the type in which the transfer is executed by utilizing heat generated by electricity.
2. Description of the Prior Art
In an electrically excited transfer recording device, a resistance layer formed in a recording film is charged with electricity by a plurality of electrode needles provided in a recording head, thereby generating heat so that ink contained in the recording film is fused by the heat and transferred onto a recording chart.
FIG. 1 depicts an end portion of one of the conventional recording heads. The recording head, generally shown by 15, is comprised of an insulating head base 16 and a plurality of electrode needles 17 disposed on the surface of the head base 6. A recording film 18 having an ink layer therein, a conductive layer and a resistance layer is pressed against a recording chart 19 by the recording head 15, with the recording chart 19 being carried by a platen 20. The recording head 15 is then charged with electricity while sliding with respect to the recording film 18. Upon generation of heat in the resistance layer, the ink contained in the ink layer is fused so that an image or images formed in the recording film 18 may be transferred onto the recording chart 19.
In this way, since the recording head 15 slides with respect to the resistance layer of the recording film 18, the resistance layer partly comes off or peels off the recording film 18 due to the heat generated by mutual friction, the electricity or the like. The resistance layer which has peeled off turns to film waste, film refuse or the like and is caused to adhere to the end portion of the recording head 15 during printing operation. Upon repeated printing operation, the film waste gradually accumulates and lowers the quality of printed image. The sliding movement between the recording head 15 and the recording film 18 wears the end portion of the recording head 15, and therefore, a length A of contact gradually increases, within which the recording film 18 is pressed against the recording chart 19. As this length A of contact increases, the pressure between the recording film 18 and the recording head 15 decreases, thus resulting in unstable contact between the recording head 15 and the recording film 18. This fact occasionally lowers the transfer properties of the ink or deteriorates the quality of the printed image.
Conventionally, certain hard ceramics such as forstelite or the like are occasionally used in the head base 16 of the recording head 15 having on its surface a plurality of electrode needles 17. In such a construction, the film waste can hardly be removed and the quality of the printed image is undesirably lowered before long. Because of this, should the occasion arise, the end portion of the recording head 15 is lapped by a grinding sheet or the like so that any particles or waste material adhering thereto may be removed for improvement of the quality of the printed image. Such work, however, consumes much time and is not only inconvenient for the user, but results in increased cost during the use of the recording device.
Furthermore, from a manufacturing aspect, the formation of a pattern of the electrode needles with respect to the hard ceramic, firing process or the like required therefor disadvantageously cost a lot.
In the case of the head base 16 employing resinous material, the sliding movement between the recording head 15 and the recording film 18 wears the end portion of the recording head 15 by a considerable amount. The length A of contact, therefore, increases relatively rapidly and the transfer properties are deteriorated before long, thus resulting in the shortened life of the recording head 15. Furthermore, the increase of the length A of contact increases the area of contact and lowers the pressure between the recording head 15 and the recording film 18. Accordingly, since it becomes troublesome to remove the film waste and the amount of adhesion or accumulation thereof, increases, the quality of the printed image tends to be deteriorate.